Finding The Lost Chestnut Bee
by Molly Jacobson
When American Chestnuts disappeared from our landscape following the spread of the infamous chestnut blight, more than just an iconic tree was presumed lost. While many recount the innumerable wildlife that depended on its plentiful nuts, few make mention of the insects that relied on it too, and one in particular – a small, unassuming brown bee that time forgot, until very recently.
Andrena rehni has no common name, as is sadly the case for a great many of our native bees. We could call it the chestnut mining bee, as it is one of the 90+ species of mining bees that call New York home, a diverse group of solitary, ground-nesting bees most often found in spring and fall but less so in midsummer (making this one stand out in more ways than one). It is also inextricably tied to chestnuts; it is a diet specialist, using only the pollen of plants in the genus Castanea as food to rear its young. Its life cycle has been molded over millennia to perfectly match the timing of the chestnut bloom period, a critical short window in late June through early July where it rushes to gather pollen and build its nest. The bee disappears soon after, its task complete, the next generation developing underground.
Records of this bee were never common, and in the past we did not realize its connection to chestnuts. But after the devastation of the blight, the bee seemed to wink out entirely, and many researchers wondered if it had quietly gone extinct. It was only in 2018, after decades of radio silence, that the chestnut mining bee was rediscovered at last, hiding out in Maryland on chinquapin, the American Chestnut’s shrubby cousin. This sparked a flurry of new interest among the scientific community, and soon new records cropped up from Connecticut and Massachusetts. Yet here in New York, there had been no sightings of the bee since 1904.
This all changed last July, when I captured not one, but six specimens of Andrena rehni from the chestnut orchard at Lasdon, as part of a larger study on chestnut pollinators. And again, this July, I was able to observe the bee at close range, foraging on chestnut catkins for that life-sustaining pollen. With this discovery comes the reinstatement of this species as an active member of New York’s native bee fauna, and perhaps equally importantly, the first living photos of this incredible little creature, which we feature here.
The great entangled web of ecological relationships species have with each other is all but invisible to us; they operate on scales both grand and miniscule, and in the hustle and bustle of modern human life few take the time necessary to witness such miraculous interactions as they play out all around us. To me it truly is a miracle that Andrena rehni is still with us, and clearly in more places than we thought, if we make an effort to look. As progress is made to someday return the American Chestnut to its rightful role as a keystone tree in our forests, I hope within our lifetimes we will see its many connections restored, and that the unique, irreplaceable community of species that depend on it will thrive once again.
